A filter contains first and second resonators adjacent to each other in a first direction, each of the first resonator and the second resonator comprising a pair of first microstrip lines formed on a first region in a second direction perpendicular to the first direction and each having an open end and other end and a first width, and a second microstrip line arranged on a second region in the second direction, and connected between other ends of the pair of first microstrip lines, and having a second width smaller than the first width, wherein a minimum distance between the first microstrip lines adjacent to the first resonator and the second resonator is set at a value smaller than a minimum distance between the second microstrip lines adjacent to the first resonator and the second resonator.
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9. A filter containing plural resonators adjacent to each other, comprising:
a first resonator and a second resonator which are arranged in proximity to each other in a first direction and fabricated on a substrate having a first region and a second region which are adjacent to each other in a second direction perpendicular to the first direction, the first region having a first width and the second region having a second width smaller than the first width, each of the first resonator and the second resonator comprising:
a pair of first microstrip lines formed on the first region having the first width larger than the second width and juxtaposed in the first direction and each of first microstrip lines having an open end and an other end and a sum of widths of the first microstrip lines and a distance between the first microstrip lines being equal to the first width; and
a second microstrip line formed on the second region having the second width smaller than the first width and connected between other ends of the pair of first microstrip lines, the second microstrip line having the second width smaller than the first width.
1. A filter containing plural resonators adjacent to each other, comprising:
a first resonator and a second resonator which are arranged in proximity to each other in a first direction and each of which is fabricated on a substrate having a first region and a second region which are adjacent to each other in a second direction perpendicular to the first direction, the first region having a first width and the second region having a second width smaller than the first width, each of the first resonator and the second resonator comprising:
a pair of first microstrip lines formed on the first region having the first width larger than the second width and juxtaposed in the first direction, each of the first microstrip lines having an open end and an other end, and a sum of widths of the first microstrip lines and a distance between the first microstrip lines being equal to the first width; and
a second microstrip line formed on the second region having the second width smaller than the first width and connected between other ends of the pair of first microstrip lines, the second microstrip line having the second width smaller than the first width of the first region,
wherein a minimum distance between one of the first microstrip lines of the first resonator adjacent to the second resonator in the first direction and one of the first microstrip lines of the second resonator that is adjacent to the one of the first microstrip lines is set at a value smaller than a minimum distance between the second microstrip line of the first resonator and the second microstrip line of the second resonator that is adjacent to the second microstrip line of the first resonator.
2. The filter according to
3. The filter according to
4. The filter according to
5. The filter according to
a plurality of first resonators containing the first resonator and a plurality of second resonators containing the second resonator are arranged in cascade between the input line and the output line with one of the first resonators being connected to the input line and one of the second resonators being connected to the output line, and
the electric length of the second microstrip line of each of the one of the first resonators and the one of the second resonators is shorter than the electric length of the second microstrip line of each of other of the first resonators and other of the second resonators.
6. The filter according to
7. A radio communication apparatus comprising:
a power amplifier to amplify a radio frequency signal;
the filter of
an antenna to transmit an output signal of the filter.
8. A radio communication apparatus comprising:
an antenna to receive a radio frequency signal;
the filter of
a low noise amplifier to amplify an output signal of the filter.
10. The filter according to
11. The filter according to
12. The filter according to
13. The filter according to
14. The filter according to
a plurality of resonators containing a plurality of first resonators and a plurality of second resonators, which are arranged in cascade between the input line and the output line with one of the first resonators being connected to the input line and one of the second resonators being connected to the output line, and
the length of the second microstrip line of each of the one of the first resonators and the one of the second resonators is shorter than the length of the second microstrip line of each of other of the first resonators and other of the second resonators.
16. A radio communication apparatus comprising:
a power amplifier to amplify a radio frequency signal;
the filter of
an antenna to transmit an output signal of the filter.
17. A radio communication apparatus comprising:
an antenna to receive a radio frequency signal;
the filter of
a low noise amplifier to amplify an output signal of the filter.
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This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2006-013767, filed Jan. 23, 2006, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a filter and a radio communication apparatus using the same.
2. Description of the Related Art
Generally, a bandpass filter in a radio communication apparatus comprises a plurality of resonators arranged in cascade. Each resonator includes an inductor and a capacitor, and further contains a resistor when an effect of a loss is considered. In the filter of this type, it is possible to determine a passband frequency range and an attenuation amount of stopband by determining an inter-resonator coupling coefficient representing a coupling quantity between adjacent resonators and a value of an external Q factor representing a quantity to excite the resonators in the input and output ports thereof properly.
A filter using a microstrip line type resonator is known as such a filter. It is desired to miniaturize the filter in the radio communication apparatus. In the filter using the microstrip line type resonator, various approaches for miniaturization of the filter are proposed.
For example, U.S. Pat. No. 6,633,208B2, FIG. 11, discloses a filter approximating a plurality of half-wavelength resonators each having a configuration such that a narrow meander line is connected between ends of a pair of broad lines. The narrow meander line is arranged between the broad lines.
U.S. Pat. No. 5,055,809 (FIGS. 7 to 15) discloses a filter approximating a plurality of half-wavelength resonators each having a configuration such that a narrow line is connected between the ends of a pair of broad lines. The narrow lines are arranged on a side opposite to the open ends of the broad lines. Further, the width of the region on which a pair of broad lines are formed equals that of the region on which the narrow lines are formed.
It is preferable that the coupling between the adjacent resonators is capacitive coupling for the filter to be miniaturized. However, according to the filter of U.S. Pat. No. 6,633,208B2, a pair of broad lines and a pair of narrow lines approximate to each other with respect to an arrangement direction of the resonators, so that the full length of the filter in the arrangement direction of the resonators increases resulting in limiting miniaturization of the filter.
In the case of the filter of U.S. Pat. No. 5,055,809, when the adjacent resonators are closed to each other for miniaturization, the capacitive coupling occurring between the adjacent resonators due to a pair of broad lines has substantially the same value as the inductive coupling occurring due to the narrow lines. As a result, the capacitive coupling and the inductive coupling are cancelled to each other so that the deviation of coupling coefficient due to the dimensional accuracy increases. The deviation of coupling coefficient deteriorates the filter characteristic, resulting in increasing fluctuation of filter characteristic at the time of production of the filter.
An aspect of the present invention provides a filter containing plural resonators adjacent to each other, comprising: a first resonator and a second resonator adjacent to each other in a first direction, which are fabricated on a substrate having a first region and a second region adjacent to each other in a second direction perpendicular to the first direction, each of the first resonator and the second resonator comprising: a pair of first microstrip lines formed on the first region in the second direction and juxtaposed in the first direction, each of the first microstrip lines having an open end and other end, and a first width; and a second microstrip line formed on the second region in the second direction and connected between other ends of the pair of first microstrip lines, the second microstrip line having a second width smaller than the first width, wherein a minimum distance between one of the first microstrip lines of the first resonator and adjacent one of the first microstrip lines of the second resonator is set at a value smaller than a minimum distance between one of the second microstrip lines of the first resonator and adjacent one of the second microstrip lines of the second resonator.
There will now be described the embodiment of the present invention referring to the drawing.
As shown in
For example, magnesium oxide or sapphire of around 0.1 mm to 1 mm in thickness is used for materials of the dielectric substrate 101. The ground plane 101, input line 103, output line 104, and resonators 105 and 106 are made of conductor materials, for example, a metal such as copper, silver, gold; a superconductor such as niobium or niobium tin; or an oxide superconductor such as YBa2Cu3O7-x.
The ground plane 102 is formed on the rear surface of the dielectric substrate 101 and the conductor pattern is formed on the front surface of the substrate 101 as described above. Such a structure is called a microstrip line structure. The conductor pattern itself formed on the front surface of the substrate 101 is referred to as a microstrip line hereinafter.
The resonators 105 and 106 are arranged in proximity to each other in a lateral direction (a direction of an arrow X) in
Wa>Wb indicates a relation between the width Wa of each of the lines 111 and 112 and the width Wb of the line 113. d1<d2 indicates a relation between the minimum length d1 between the first regions 201 of the resonators 105 and 106 (i.e., minimum length between the line 112 of the resonator 105 and the line 111 of the resonator 106 adjacent thereto) and the minimum length d2 between the second regions (minimum length between the lines 113 of the resonators 105 and 106). In
There will be explained an operation of the filter shown in
The resonators 105 and 106 are expressed with an inductor and a capacitor in equivalent as shown in
f0=1/sqrt(L×C) (1)
where f0 indicates a resonance frequency, sqrt a square root, L an inductance, C a capacitance, respectively.
It is possible to determine a passband frequency range of a filter and a magnitude of attenuation of stopband by determining properly an external Q factor m1 when viewed the initial stage (first stage) resonator 105 from the input terminal 11, an external Q factor m1 when viewed the initial stage (fourth stage) resonator 106 from the input terminal 13, and an inter-resonator coupling coefficient m2 representing a coupling quantity between the resonators 105 and 106.
In an equivalent circuit of a half-wavelength resonator 20 shown in
As shown in
The shortest distance between the first regions of the resonators 105 and 106, that is, distance between the open end of the line 112 of the resonator 105 and the open end of the line 111 of the resonator 106 is d1. In other words, the maximum voltage points at the open ends of the half-wavelength resonators approach to each other with the distance d1. As a result, the capacitive coupling between the resonators 105 and 106 can be realized.
On the other hand, the shortest distance between the second regions of the resonators 105 and 106, that is, distance between the line 112 of the resonator 105 and the line 111 of the resonator 106 is d2. In other words, the maximum current points at the intermediate positions of the half-wavelength resonators approach to each other. As a result, the inductive coupling between the resonators 105 and 106 can be realized.
As explained above, generally when adjacent two resonators are miniaturized, capacitive and inductive couplings occur. When both of the capacitive and inductive couplings are cancelled to each other, a change of the coupling quantity (coupling coefficient) increases.
As shown in
Because the inductive coupling is easy to be produced between the adjacent resonators and the other resonators other than the adjacent resonators, it is effective to use only capacitive coupling in a filter for a desired coupling coefficient to be formed between the adjacent resonances. In the filter shown in
Further, when the length W2 of the second region 202 in an X-direction is set at a range of not more than 90% of the length W1 of the first region, it is possible to realize coupling similar to the case of only capacitive coupling in a range of coupling coefficient to be necessary to configure a general filter.
Further, in the filter of
A filter of another embodiment will be described referring to
The filter shown in
The relation (Wa>Wb) of the width Wa of the lines 111 and 112 and the width Wb of the line 113, the relation (d1<d2) of the shortest distance d1 between the first regions of the resonators 105 and 106 and the shortest distance d2 between the second regions 202, and the total electric length of the lines 111, 112 and 113 which is approximately half-wave length are similar to the previous embodiment. Accordingly, the filter of
On the other hand, the coupling of the resonators 105 and 107 is realized only by coupling the line 112 of the resonator 107 with the line 111 of the resonator 105. Similarly, the coupling of the resonators 106 and 108 is realized only by coupling the line 111 of the resonator 108 with the line 112 of the resonator 106.
Coupling of the input line 103 with the first stage resonator 107 and coupling of the output line 104 with the second resonator 108 are called an external Q coupling. A small external Q is required in realizing a filter of a broad band, and the resonators 107 and 108 must be strongly coupled with the input line 103 and the output line 104, respectively, to provide the external Q. If strong coupling is realized, the resonance frequency of the resonator largely falls. Therefore, in the filter of
Generally, when a filter is fabricated using three or more resonators as shown in
An embodiment wherein the filter is applied to a radio communication apparatus is explained referring to
The RF signal output from the mixer 502 is amplified with a power amplifier 504 and input to a bandpass filter (transmission filter) 505 and band-limited thereby to remove an unnecessary frequency component. The resultant signal is supplied to an antenna 506. The bandpass filter 505 can use a filter explained in the above embodiment.
A receiver of the radio communication apparatus is explained referring to
A signal received with the antenna is input to a bandpass filter (receive filter) 508 and band-limited thereby to remove an unnecessary frequency component, and then input to a low noise signal amplifier 507. The received signal is amplified with the low noise signal amplifier 507. The amplified received signal is input to a mixer 502 and multiplied by a local signal to be converted to a baseband or an intermediate frequency. The signal of low frequency is input to the signal processor 501 and demodulated therein. The demodulated signal is output from the signal processor 501 as receive data 509. The bandpass filter 508 can use the filter explained in the above embodiment.
According to the present invention, the filter can be easy miniaturized, and the change of the coupling coefficient due to accuracy of dimension between adjacent resonators is decreased. Further, shortening of adjustment time of the filter and improvement of yield can be realized.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
Patent | Priority | Assignee | Title |
9093973, | May 11 2011 | Panasonic Corporation | Electromagnetic resonance coupler |
9325045, | Apr 12 2013 | Kabushiki Kaisha Toshiba | Filter and resonator |
Patent | Priority | Assignee | Title |
5055809, | Aug 04 1988 | Matsushita Electric Industrial Co., Ltd. | Resonator and a filter including the same |
5786303, | Jun 22 1994 | Com Dev Ltd. | Planar multi-resonator bandpass filter |
6026311, | May 28 1993 | RESONANT, INC | High temperature superconducting structures and methods for high Q, reduced intermodulation resonators and filters |
6122533, | Jun 28 1996 | ISCO INTERNATIONAL, INC | Superconductive planar radio frequency filter having resonators with folded legs |
6603373, | May 11 2000 | Murata Manufacturing Co., Ltd. | Adjusting method for electrical characteristics of microstrip line filter, duplexer, communication device, and microstrip line type resonator |
6633208, | Jun 19 2001 | RESONANT, INC | Filter with improved intermodulation distortion characteristics and methods of making the improved filter |
6653912, | Nov 03 2000 | NXP USA, INC | RF and microwave duplexers that operate in accordance with a channel frequency allocation method |
6720849, | Nov 14 2000 | Murata Manufacturing Co. Ltd. | High frequency filter, filter device, and electronic apparatus incorporating the same |
6980841, | Mar 05 2002 | Fujitsu Limited | Filter device having spiral resonators connected by a linear section |
RE37636, | Jun 15 1993 | Detroit Radiant Products Company | Demand radiant heating system |
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Sep 25 2006 | KAYANO, HIROYUKI | Kabushiki Kaisha Toshiba | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 018603 | /0473 |
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